Tactics Skill
You could call this your knowledge of combat tactics. To learn it you have to actually fight, and that is how you develop your tactics. In general you gain faster while fighting two enemies at once and switching your attack between them. As a rule, gains start as soon as you use any warrior skill. 100 Tactics grants a %50 Damage bonus.
It is not fast like Fencing nor slow like Mace Fighting, it sits right in the middle. It became especially valuable among the warrior types after Samurai Empire. Lumberjacking and Tactics are what you need to push your damage up.